Did hydrothermal vents push the frontiers of habitability on the early Earth?

氮（N）和磷（P）是地球上所有生命的必需营养素。这些营养素的缺乏会限制生物生产力，而无限制的供应会导致细菌大量繁殖，对环境造成严重影响。因此，研究氮和磷循环对于从生命起源到现代环境变化的主题至关重要。因此，这项研究计划的目的是（a）建立一个新的分析中心，包括实验设施的N和P地球化学，（B）应用这些工具来调查未充分探索的途径N和P循环，（c）将生物信息学数据，以重建稀有P物种的生物利用。拟议项目将是新分析设施的第一批应用。这个项目的主旨是早期生命是如何维持的基本问题。几条证据表明，在整个前寒武纪，初级生产力受到严重抑制，因为磷酸盐和硝酸盐--现代海洋中P和N的两种主要形式--在古代海洋中的溶解度要低得多。我们假设，海底火山活动，通过海洋地壳掀起热液对流细胞，产生还原形式的氮和磷，从而创造了重要的点源营养物质的早期生命。为了验证这一假设，我们将开发一个新的热液反应室，使我们能够在高压和高温下进行实验，让人想起深海热液喷口。不同的气体（N2、CO2、CH 4）、流体（盐水、新鲜）、磷酸盐相和催化矿物（磁铁矿、硫化物）将在一系列条件下加入反应器。将对产物进行氮同位素比率（15 N/14 N）和磷形态分析，主要目标是：* 测量与非生物热液N2还原为铵和有机胺有关的同位素分馏。这些结果将使我们能够重新访问现有的N同位素记录（包括富含有机物的沉积岩和热液影响的地层），并确定热液N源是否在前寒武纪地球化学循环中发挥了重要作用。定量水热磷酸盐还原为亚磷酸盐的产率。亚磷酸盐是磷的还原形式，比磷酸盐更易溶解。以前的实验表明，亚磷酸盐可以由简单磷酸盐的还原产生。我们将用天然磷酸盐矿物进行新的实验，以获得热液情景的反应效率。我们还将测量有多少亚磷酸盐被吸收到矿物中，以建立岩石记录中磷酸盐地球化学测量的校准。重建亚磷酸盐的辐射-使用酶横跨生命之树。系统发育数据和分子钟将用于推断相关基因的诞生、丢失和转移。这项分析将揭示，如果亚磷酸盐利用确实规模与早期地球上的热液活动的程度，这将支持我们的假设的热液亚磷酸盐sources. Results从这项工作将推进我们的理解早期生命是如何维持的。如果我们能够证明热液喷口是生物可利用的亚磷酸盐和还原氮的重要来源，这将对其他火山活跃行星的可居住性产生重大影响。将在该项目的保护伞下开发和优化的分析设置将为未来研究古代和现代营养循环开辟更多的可能性。例如，实验装置将允许研究关键金属在水热条件下的行为，分析套件将为研究现代污染环境中的N和P循环创造新的机会。因此，这些设施将在英国建立一个新的分析中心，并将PI置于地球化学研究的前沿。

Nitrogen (N) and phosphorus (P) are essential nutrients to all life on Earth. Scarcity of these nutrients can limit biological productivity while unrestricted supplies can lead to bacterial blooms with severe environmental impacts. Investigating the N and P cycles is therefore critical for topics ranging from life's origins to modern environmental change. The aim of this research programme is therefore to (a) create a new analytical centre for N and P geochemistry, including experimental facilities, (b) apply these tools to investigate underexplored pathways of N and P cycling, and (c) incorporate bioinformatic data to reconstruct the biological utilisation of rare P species. The proposed project will represent the first set of applications of the new analytical facilities. The major thrust of this project is the fundamental question how early life was sustained. Several lines of evidence suggest that primary productivity was severely suppressed throughout the Precambrian, because phosphate and nitrate - the two major forms of P and N in the modern ocean - were much less soluble in ancient oceans. We hypothesise that submarine volcanism, which sets off hydrothermal convection cells through oceanic crust, generated reduced forms of nitrogen and phosphorus and thus created important point sources of nutrients for early life. To test this hypothesis, we will develop a new hydrothermal reaction chamber that allows us to conduct experiments under elevated pressures and temperatures, reminiscent of deep-sea hydrothermal vents. Different gases (N2, CO2, CH4), fluids (saline, fresh), phosphate phases and catalytic minerals (magnetite, sulphides) will be added to the reactor under a range of conditions. The products will be analysed for nitrogen isotopic ratios (15N/14N) and phosphorus speciation.The main objectives are:* Measure the isotopic fractionation associated with abiotic hydrothermal N2 reduction to ammonium and organic amines. These results will allow us to re-visit the existing N isotopic record (including organic-rich sedimentary rocks and hydrothermally influenced strata) and determine if hydrothermal N sources played a significant role in Precambrian biogeochemical cycles.* Quantify the yield of hydrothermal phosphate reduction to phosphite. Phosphite, a reduced form of P, is significantly more soluble than phosphate. Previous experiments have shown that phosphite can be produced from the reduction of simple phosphate salts. We will conduct new experiments with natural phosphate minerals to derive reaction efficiencies for hydrothermal scenarios. We will also measure how much phosphite is taken up into minerals to create a calibration for geochemical measurements of phosphate in the rock record.* Reconstruct the radiation of phosphite-using enzymes across the tree of life. Phylogenetic data and molecular clocks will be used to infer the birth, loss and transfer of relevant genes. This analysis will reveal if phosphite utilisation did indeed scale with the extent of hydrothermal activity on early Earth, which would support our hypothesis of hydrothermal phosphite sources.The results from this work will advance our understanding of how early life was sustained. If we can show that hydrothermal vents are significant sources of bioavailable phosphite and reduced nitrogen, this would have major implications for the habitability of other volcanically active planets. The analytical setup that will be developed and optimised under the umbrella of this project would open up further possibilities for future studies of ancient and modern nutrient cycling. For example, the experimental setup will allow investigating the behaviour of critical metals under hydrothermal conditions, and the analytical suite will create new opportunities to study N and P cycling in modern polluted settings. The facilities would thus create a new analytical centre in the UK and place the PI at the frontier of biogeochemical research.